1. Field of the Invention
The present invention relates to devices for inducing hypothermia
2. Description of the Related Art
Strokes, Traumatic Brain injury, and Spinal Injury commonly pose significant risk of permanent damage to the spinal cord and brain. Similarly, multiple diseases/events/procedures including but not limited to heart disease, cardiac arrest, and major surgery may be followed by cerebral and spinal cord ischemia, which in turn can lead to permanent neurologic damage. Recovery from severe brain injury resulting from ischemia, stroke, hemorrhage, or trauma is uncommon. The permanence and untreatable nature of neurologic injury requires speedy mitigating treatment and care.
It has long been believed that hypothermia may mitigate brain damage. Treatment by mild hypothermia after cardiac arrest was initially reported in the late 1950s and early 1960s. The Hypothermia after Cardiac Arrest Study Group, “Mild Therapeutic Hypothermia to Improve the Neurologic Outcome after Cardiac Arrest.” New England Journal of Medicine 346.8 (2002): 549-56. The reason for its benefits have not been proven, but induction of mild hypothermia has been hypothesized to significantly decrease intracranial pressure and secondary neurological injury in various types of brain injury, including traumatic brain injury, ischemic stroke, intracranial hemorrhage, and hepatic encephalopathy. Thus, hypothermia continues to be a hopeful tool to prevent, protect against, or mitigate neurologic injury.
In tact, induction of systemic hypothermia, i.e. hypothermia induced to the whole body, is an accepted initial step in the management of patients who survive cardiac arrest. Devices for inducing systemic hypothermia include cooling pads and vascular catheters. Systemic hypothermia is associated, however, with a host of negative side effects including bleeding diathesis, shivering, arrhythmias, suppression of the immune system resulting in increased susceptibility to infection, and electrolyte imbalance.
Thus, there is growing, interest in techniques that would provide neuroprotective benefits without the harmful side effects of systemic hypothermia. Currently known devices for selective cooling of the nervous system include cooling helmets and catheters that circulate cooled saline, but have been of limited efficacy due to failure to consistently dissipate heat or adverse side effects. Furthermore, methods using circulating liquids are limited by the freezing point of the liquid, and risk rupture and contamination.